US5069884A - Process for the purification of an aqueous alkali metal chloride solution from ammonium and iodine compounds - Google Patents

Process for the purification of an aqueous alkali metal chloride solution from ammonium and iodine compounds Download PDF

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Publication number
US5069884A
US5069884A US07/520,526 US52052690A US5069884A US 5069884 A US5069884 A US 5069884A US 52052690 A US52052690 A US 52052690A US 5069884 A US5069884 A US 5069884A
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stage
alkali metal
iodine
compounds
chloride solution
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Mauro Filippone
Carlo Lessi
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Solvay SA
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Solvay SA
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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
    • C01D3/00—Halides of sodium, potassium or alkali metals in general
    • C01D3/14—Purification
    • C01D3/145—Purification by solid ion-exchangers or solid chelating agents
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
    • C01D3/00—Halides of sodium, potassium or alkali metals in general
    • C01D3/14—Purification

Definitions

  • the invention relates to the purification of aqueous alkali metal chloride solutions such as sodium chloride brines.
  • It relates more particularly to a process for the purification of an aqueous alkali metal chloride solution from ammonium and iodine compounds.
  • Aqueous sodium chloride solutions obtained from seawater or by dissolving rock salt in water contain various impurities, which include especially calcium, magnesium, iron and ammonium compounds (aqueous ammonia, ammonium chloride), iodine compounds (metal iodides) and bromine compounds (metal bromides). These impurities are harmful when the sodium chloride solutions are treated in electrolysis cells to produce chlorine and sodium hydroxide. In particular, ammonium compounds, iodine compounds and bromine compounds then form nitrogen trichloride, iodine and bromine, which enter the chlorine and contaminate.
  • impurities include especially calcium, magnesium, iron and ammonium compounds (aqueous ammonia, ammonium chloride), iodine compounds (metal iodides) and bromine compounds (metal bromides).
  • impurities include especially calcium, magnesium, iron and ammonium compounds (aqueous ammonia, ammonium chloride), iodine compounds (metal iodides)
  • the invention relates to a process for the purification of an aqueous alkali metal chloride solution from iodine compounds and from ammonium compounds, in which the iodine compounds and the ammonium compounds are oxidized and the iodine and nitrogen which are produced are removed, respectively, on a halogenated basic anion exchange resin and in a stream of inert gas; according to the invention, the operation is carried out in two successive stages comprising a first stage in which the iodine compounds are oxidized and the resulting alkali metal chloride solution is then treated on the resin and a second stage in which the ammonium compounds are oxidized and the resulting alkali metal chloride solution is then subjected to the stream of inert gas.
  • ammonium and iodine compounds comprise aqueous ammonia, ammonium chloride and metal, especially alkali metal, iodides. They are naturally present in seawater or rock salt when the aqueous solution of alkali metal is an aqueous sodium chloride solution.
  • the oxidation of the iodine compounds is preferably carried out using active chlorine, generally in acidic medium. Chlorine or alkali metal hypochlorite may be employed for this purpose. Sodium hypochlorite is preferred.
  • the oxidation is controlled so as to decompose the iodine compounds and to form molecular iodine; it is expressly appropriate to avoid an excessive oxidation leading to the formation of IO 3 - . This condition is imposed because IO 3 - anions are not adsorbed on the anion exchange resin employed in the process. To this end, the oxidation may, for example, be followed and accurately controlled using a measurement of the redox potential of the reaction mixture.
  • the anionic resin is a basic resin comprising fixed cationic sites and interchangeable anionic sites, occupied by halogen anions, such as BR - , Cl - and I - .
  • Anion exchange resins which can be employed in the process according to the invention are those in which the fixed cationic sites are quaternary ammonium groups attached to long-chain polymers such as copolymers of styrene and divinylbenzene. Resins of this type are described in U.S. Pat. Nos.
  • Amberlite resins (Rohm & Haas Co) are suitable, in particular the varieties known in the trade under the trademarks Amberlite IRA-400, Dowex-1, Duolite A-42, Nalcite SBR and Permutite S-1.
  • the resin is generally in the form of granules, in contact with which the aqueous sodium chloride solution is circulated.
  • the resin employed in the process according to the invention must have its interchangeable sites occupied by halogen anions. Chloride and iodide anions are preferred. The adsorption of free iodine from the solution onto the resin takes place with formation of polyhalogenated complexes, probably according to the following reaction:
  • I 2 denotes molecular iodine from the aqueous solution
  • R + denotes a fixed cationic site of the resin
  • X - denotes a halide ion occupying an interchangeable anionic site of the resin (for example an I - or Cl - ion).
  • the resin must be regenerated at regular intervals when its sites are saturated with the (XI 2n ) - anions.
  • the regeneration can be obtained by washing the resin with a solvent in which iodine is more soluble than water, for example an alcohol, or with an iodine reagent. Additional information on the resin and its use is available in Patent GB-A-893,692.
  • the aqueous solution collected at the end of the treatment on the anion exchange resin is then subjected to the second stage of the process according to the invention.
  • the oxidation of the ammonium compounds is also preferably carried out by means of active chlorine, generally in acidic medium, for example by means of a stream of chlorine or of alkali metal hypochlorite. Sodium hypochlorite is preferred.
  • the oxidation is controlled so as to decompose the ammonium compounds and to liberate nitrogen, for example according to the reactions:
  • inert gas is intended to mean a gas which does not react with the constituents of the aqueous solution and which does not constitute a harmful impurity for the application for which the solution is intended.
  • inert gases which may be employed in the process according to the invention are oxygen, air, argon and steam. Air is preferred.
  • the process according to the invention is preferably applied to aqueous solutions which have been purified from calcium and magnesium beforehand.
  • the first stage of the process of the invention may be preceded by a treatment of the solution with sodium carbonate and sodium hydroxide, as is well known in the art (J. S. Sconce - Chlorine, Its manufacture, Properties and Uses - Reinhold Publishing Corporation - 1962 - Pages 135 and 136).
  • the aqueous sodium chloride solution is subjected to a debromination stage, in addition to the abovementioned two stages.
  • the purpose of the debromination stage is to purify the aqueous solution from bromine compounds by removing the bromide ions which it contains.
  • the debromination stage follows the abovementioned first stage and comprises an oxidation of the bromine compounds in the solution to bromine, followed by a treatment of the resulting solution on a halogenated basic anion exchange resin.
  • the oxidation of the bromine compounds and the subsequent treatment of the aqueous solution on the anion exchange resin may be carried out in a manner similar to the first stage of the process, which is described above.
  • the oxidation is preferably carried out with active chlorine in acidic medium, for example by means of gaseous chlorine or alkali metal hypochlorite, sodium hypochlorite being the preferred oxidizing agent.
  • the oxidation must be controlled to decompose the bromine compounds and to form molecular bromine, while expressly avoiding an excessive oxidation leading to the formation of BrO 3 - anions.
  • the resin is of the type of those described above with reference to the first stage of the process.
  • the debromination stage may follow the abovementioned second stage or may be inserted between the first stage and the second stage.
  • the pH of the aqueous solution constitutes a parameter which is of importance for the efficiency of purification.
  • it has been found especially advantageous to carry out each of the stages of the process in acidic medium the pH being lower than 3 in the first stage and higher than 2 in the second stage.
  • Preferred pH values are those between 0.5 and 3 in the first stage, between 2 and 6 in the second stage and, if appropriate, between 1 and 6 in the debromination stage.
  • the optimum pH values at each stage of the process depend on the operating conditions and can be readily determined by routine laboratory tests.
  • the invention finds an advantageous application for the purification of aqueous sodium chloride solutions intended for the manufacture of sodium carbonate by the aqueous ammonia process, and for the production of chlorine and sodium hydroxide by electrolysis.
  • the figure is a diagram of the process according to the present invention.
  • the plan shown diagrammatically in the figure is intended to purify an aqueous sodium chloride solution contaminated with calcium and magnesium compounds (CaCl 2 , MgCl 2 ), ammonium compounds (NH 4 OH, NH 4 Cl) and bromine and iodine compounds (sodium, calcium and magnesium iodides).
  • It comprises a reaction chamber 1 in which the aqueous sodium chloride solution 2 is treated with sodium carbonate 3 and with sodium hydroxide 4 to precipitate the calcium and magnesium ions as calcium carbonate and magnesium hydroxide
  • the aqueous suspension 5 collected from the reaction chamber 1 is transferred to a settling chamber 6, to separate off the precipitate 7 of calcium carbonate and magnesium hydroxide.
  • An aqueous sodium chloride solution 8 is collected from the settling chamber 6 and is introduced into the reaction chamber 9; in the latter the solution is acidified to a suitable pH and treated by the addition of an aqueous sodium hypochlorite solution 10 to oxidize the iodide ions to molecular iodine.
  • the quantity of sodium hypochlorite employed is controlled by a measurement of the redox potential of the reaction mixture so as to produce a substantially complete oxidation of the iodide anions I - to iodine while avoiding the formation of iodate anions IO 3 - .
  • the aqueous sodium chloride solution is then introduced into a column 11 filled with beads of an anion exchange resin whose interchangeable sites are saturated with halogen anions (I - , Br - , Cl - ). In the column the solution percolates through the resin and the iodine is progressively adsorbed on the latter.
  • the aqueous sodium chloride solution 12 collected at the foot of the column 11 is conveyed to a reactor 13 where, after pH adjustment, an aqueous sodium hypochlorite solution 14 is added to it in a sufficient quantity to decompose the ammonium compounds and to liberate nitrogen
  • the aqueous solution is introduced into the top of a column 15 fed with a stream of air 16 at the base.
  • the aqueous solution is subjected to scrubbing by the current of air which thus entrains the nitrogen out of the solution.
  • the nitrogen-charged air (21) escapes at the head of the column 15.
  • the aqueous solution run off at the foot of the column 15 is introduced into an additional reactor 17, where an aqueous sodium hypochlorite solution 18 is added to it in a quantity adjusted so as to oxidize the bromide ions to molecular bromine while avoiding the formation of complex bromate anions BrO 3 - .
  • the solution leaving the reactor 17 is introduced into a column 19 where it is percolated through a basic anion exchange resin whose interchangeable sites are occupied by halogen anions. The bromine of the brine is thus adsorbed onto the resin and an aqueous sodium chloride solution 20 of high purity is collected at the foot of the column.
  • Examples 1 to 3 relate to tests in which aqueous sodium chloride solutions were subjected to a purification process in accordance with the invention. To this end, they were treated in a plant of the type of that described above with reference to the attached drawing, where they were subjected successively to:
  • bromate ions ⁇ 0.2 mg/l
  • ammonium ions 28 mg/l (expressed as NH 3 ).
  • the aqueous solution was brought to an acidic pH and was treated with a stream of chlorine whose flow rate was adjusted to a suitable value for oxidizing all the iodide ions to iodine while avoiding the formation of iodate anions.
  • the control of the flow rate of chlorine was carried out using a measurement of the redox potential of the reaction mixture, as explained above.
  • the aqueous solution was then treated on an Amberlite IRA-400 (Rohm & Haas) anion exchange resin.
  • the iodine content of the aqueous solution leaving the resin was 0.5 mg/l.
  • the aqueous solution was then subjected to the stage of purification from aqueous ammonia. In this stage it was treated with a stream of chlorine whose flow rate was controlled using a measurement of the redox potential at a sufficient value to oxidize all the ammonium cations while liberating nitrogen
  • the aqueous solution was then subjected to a scrubbing with an upward stream of air at a flow rate of 200 l/h.
  • An ammonium ion content (expressed in mg of NH 4 ) of less than 0.2 mg/l was measured in the solution collected at the foot of the column.
  • the aqueous solution was treated with a stream of chlorine whose flow rate was controlled using a measurement of the redox potential at a suitable value for completing the oxidation of the bromide ions to bromine while avoiding forming bromate anions.
  • the aqueous solution was then treated on an Amberlite IRA-400 (Rohm & Haas) anion exchange resin.
  • the aqueous solution collected at the exit from the resin contained, per liter:
  • Example 1 The test of Example 1 was repeated with an aqueous sodium chloride solution containing the following impurities:
  • bromate ions ⁇ 0.2 mg/l
  • ammonium ions 28 mg/l (expressed as NH 3 ).
  • Example 1 The test of Example 1 was repeated with an aqueous sodium chloride solution containing the following impurities:
  • bromate ions 0.3 mg/l
  • ammonium ions 27 mg/l (expressed as NH 3 ).
  • ammonium ions 27 mg/l (expressed as NH 3 ).
  • the stage of purification from aqueous ammonia was performed as in the tests of Examples 1 to 3, the flow rate of scrubbing air being equal to 200 l/h.
  • the stages of purification from iodine and bromine were performed as in the tests relating to Examples 1 to 3.
  • Example 4 The test of Example 4 was repeated with an aqueous sodium chloride solution containing the following impurities:
  • ammonium ions 31 mg/l (expressed as NH 3 ).
  • the hourly flow rate of the solution was 20 liters.
  • Example 4 The test of Example 4 was repeated with an aqueous sodium chloride solution containing the following impurities:
  • ammonium ions 27 mg/l (expressed as NH 3 ).
  • the hourly flow rate of the solution was 10 liters.
  • the stage of purification from aqueous ammonia was performed as in the tests of Examples 1 to 5, but the purification from iodine and the purification from bromine were performed simultaneously in a single stage which followed the stage of purification from ammonia.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Inorganic Chemistry (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
  • Removal Of Specific Substances (AREA)
  • Treating Waste Gases (AREA)
  • Detergent Compositions (AREA)
  • Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
  • Treatment Of Water By Ion Exchange (AREA)
  • Inorganic Compounds Of Heavy Metals (AREA)
  • Treatment Of Water By Oxidation Or Reduction (AREA)
  • Manufacture And Refinement Of Metals (AREA)
  • Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
US07/520,526 1989-05-15 1990-05-08 Process for the purification of an aqueous alkali metal chloride solution from ammonium and iodine compounds Expired - Lifetime US5069884A (en)

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Application Number Priority Date Filing Date Title
IT20504A/89 1989-05-15
IT8920504A IT1229724B (it) 1989-05-15 1989-05-15 Procedimento di purificazione di una soluzione acquosa di cloruro di un metallo alcalino da composti ammoniacali e iodati.

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US (1) US5069884A (de)
EP (1) EP0399588B1 (de)
JP (1) JP3021540B2 (de)
AT (1) ATE93494T1 (de)
BR (1) BR9002207A (de)
CA (1) CA2016670C (de)
DE (1) DE69002870T2 (de)
DK (1) DK0399588T3 (de)
ES (1) ES2045758T3 (de)
IT (1) IT1229724B (de)
PT (1) PT94029B (de)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5445741A (en) * 1992-12-30 1995-08-29 Solvay Deutschland Gmbh Process for treating waste water
US6455022B1 (en) * 1991-06-10 2002-09-24 Elf Atochem S.A. Purification of aqueous alkali metal chloride solutions by removal of ammonium/iodine values therefrom
DE19839513B4 (de) * 1998-08-29 2007-12-13 Schüssler Entsorgungs-Management und Rohstoffhandel GmbH Verfahren und Anlage zur Entbromung von Magnesiumchloridlösung
US20100119438A1 (en) * 2008-11-12 2010-05-13 Becker Thomas M Iodine recovery system
EP2481837A2 (de) 2011-01-26 2012-08-01 Superior Plus LP Verfahren zum Herstellen von Chlorin mit geringem Bromgehalt
US8636893B2 (en) 2011-01-26 2014-01-28 Superior Plus Lp Process for producing chlorine with low bromine content
US20170096346A1 (en) * 2015-10-05 2017-04-06 The Chemours Company Tt, Llc Purification of nacl brine containing iodine

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4110177C2 (de) * 1991-03-27 1995-01-05 Qvf Glastech Gmbh Verfahren zur Herstellung einer von Fremdhalogenen gereinigten Salzsäure
FR2692879B1 (fr) * 1992-06-26 1994-12-02 Atochem Elf Sa Procédé de purification d'une solution aqueuse de chlorure de métal alcalin pour enlever l'iode.
IT1265291B1 (it) * 1993-12-17 1996-10-31 Solvay Procedimento e impianto per la depurazione di una soluzione acquosa di un cloruro di un metallo alcalino
JP3390148B2 (ja) 1998-08-28 2003-03-24 クロリンエンジニアズ株式会社 電解用塩水の精製処理方法
FR2894247B1 (fr) * 2005-12-07 2008-02-15 Solvay Procede pour l'epuration d'une solution aqueuse chargee en iodure, calcium, magnesium
CN104528765B (zh) * 2014-12-24 2016-03-23 湖北双环科技股份有限公司 一种氨碱-联碱循环生产工艺及其应用

Citations (7)

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Publication number Priority date Publication date Assignee Title
BE674933A (de) *
US1861763A (en) * 1931-05-13 1932-06-07 Solvay Process Co Process of treating brine
US3174828A (en) * 1960-08-31 1965-03-23 Du Pont Sorption of bromine on anion exchange resins in the presence of excess chlorine
US3346331A (en) * 1964-05-04 1967-10-10 Rohm & Haas Recovery of iodine from solutions containing same
US4131645A (en) * 1974-11-21 1978-12-26 Ethyl Corporation Iodine recovery process
JPS5424995A (en) * 1977-07-27 1979-02-24 Showa Denko Kk Production of propylene copolymer
SU1154202A1 (ru) * 1983-12-06 1985-05-07 Всесоюзный Заочный Политехнический Институт Способ извлечени брома из рассола

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE674933A (de) *
US1861763A (en) * 1931-05-13 1932-06-07 Solvay Process Co Process of treating brine
US3174828A (en) * 1960-08-31 1965-03-23 Du Pont Sorption of bromine on anion exchange resins in the presence of excess chlorine
US3346331A (en) * 1964-05-04 1967-10-10 Rohm & Haas Recovery of iodine from solutions containing same
US4131645A (en) * 1974-11-21 1978-12-26 Ethyl Corporation Iodine recovery process
JPS5424995A (en) * 1977-07-27 1979-02-24 Showa Denko Kk Production of propylene copolymer
SU1154202A1 (ru) * 1983-12-06 1985-05-07 Всесоюзный Заочный Политехнический Институт Способ извлечени брома из рассола

Non-Patent Citations (6)

* Cited by examiner, † Cited by third party
Title
Chemical Abstracts, vol. 42, No. 3, 10 fevrier 1948, colonne 1030i, Columbus Ohio, US; E. Urion et al.: "Purification of Brines Contaminated with Ammonia", & Chimie & Industrie 58, 348 (1947).
Chemical Abstracts, vol. 42, No. 3, 10 fevrier 1948, colonne 1030i, Columbus Ohio, US; E. Urion et al.: Purification of Brines Contaminated with Ammonia , & Chimie & Industrie 58, 348 (1947). *
Chemical Abstracts, vol. 92, No. 8, 8 Fevrier 1980, p. 138, Resume No. 61134t, Columbus, Ohio, US; & JP A 79 24 995 (Mitsui Toatsu Chemicals, Inc.), 24 08 1979. *
Chemical Abstracts, vol. 92, No. 8, 8 Fevrier 1980, p. 138, Resume No. 61134t, Columbus, Ohio, US; & JP-A-79 24 995 (Mitsui Toatsu Chemicals, Inc.), 24-08-1979.
Delayed Belgian Report, General Inorganic, FTC p. 1, No. 28/66, Abstract of BE 674933. *
Delayed Belgian Report, General Inorganic, FTC-p. 1, No. 28/66, Abstract of BE-674933.

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6455022B1 (en) * 1991-06-10 2002-09-24 Elf Atochem S.A. Purification of aqueous alkali metal chloride solutions by removal of ammonium/iodine values therefrom
US5445741A (en) * 1992-12-30 1995-08-29 Solvay Deutschland Gmbh Process for treating waste water
DE19839513B4 (de) * 1998-08-29 2007-12-13 Schüssler Entsorgungs-Management und Rohstoffhandel GmbH Verfahren und Anlage zur Entbromung von Magnesiumchloridlösung
US20100119438A1 (en) * 2008-11-12 2010-05-13 Becker Thomas M Iodine recovery system
EP2481837A2 (de) 2011-01-26 2012-08-01 Superior Plus LP Verfahren zum Herstellen von Chlorin mit geringem Bromgehalt
US8636893B2 (en) 2011-01-26 2014-01-28 Superior Plus Lp Process for producing chlorine with low bromine content
US20170096346A1 (en) * 2015-10-05 2017-04-06 The Chemours Company Tt, Llc Purification of nacl brine containing iodine
US11040903B2 (en) * 2015-10-05 2021-06-22 The Chemours Company Fc, Llc Purification of NaCl brine containing iodine

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Publication number Publication date
EP0399588A1 (de) 1990-11-28
BR9002207A (pt) 1991-08-13
ATE93494T1 (de) 1993-09-15
CA2016670C (fr) 2000-11-07
DE69002870D1 (de) 1993-09-30
PT94029B (pt) 1996-12-31
DE69002870T2 (de) 1994-03-17
PT94029A (pt) 1991-01-08
CA2016670A1 (fr) 1990-11-15
JP3021540B2 (ja) 2000-03-15
IT8920504A0 (it) 1989-05-15
JPH0350114A (ja) 1991-03-04
DK0399588T3 (da) 1994-01-10
IT1229724B (it) 1991-09-07
EP0399588B1 (de) 1993-08-25
ES2045758T3 (es) 1994-01-16

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